1. Field of the Invention
The present invention relates to a recording medium suitable to ink jet recording.
Furthermore, the present invention relates to a production method of the recording medium and an image formation method using the recording medium.
2. Related Background Art
Recently, an ink jet recording system, in which print images, characters, and the like are recorded by ejecting micro drops of ink in accordance with various operating principles and applying the micro drops to a recording medium such as paper, has rapidly become widespread in various applications as well as information-processing equipment as recording equipment for various images. It is because the ink jet recording system has advantages such as high-speed and low noise, easy multi-color printing, large flexibility in printing pattern, and unnecessity of development and fixing. Furthermore, it is also possible to obtain images formed by a multi-color ink jet recording system, which are not inferior to multi-color prints by a plate-making system and photoprints by a color photographic system. Moreover, if the number of printing media is small, the prints by the ink jet recording system is less expensive than the ordinary multi-color prints and photoprints, and hence have been widely applied even to the field of a fill-color image recording. Although ink jet recording apparatuses and printing methods have been improved with the improvement in recording characteristics in terms of sensitivity such as high-speed recording, high-resolution recording, and full-color recording, printing media also have been required to have advanced characteristics.
Recently, printing media having a coating layer made of aluminum hydrate with boehmite structure have been proposed. For example, they are disclosed in U.S. Pat. Nos. 4879166 and 5104730 and Japanese Patent Application Laid-Open Nos. 2-276670, 4-37576, and 5-32037.
A recording medium with this aluminum hydrate has such advantages as firm fixing of dyes in ink due to positive charges in the aluminum hydrate, good transparency of an ink receiving layer containing the aluminum hydrate and thick print density, and an image having good color development can be obtained. In addition, there are no problems such as browning of black ink and degradation of light resistance, which are heretofore caused by silica compounds conventionally used, and this medium is superior to a conventional recording medium in terms of image quality, in particular, that in an full-color image, gloss, and applicability to an OHP sheet.
Nevertheless, in order to fully make use of the advantages of this aluminum hydrate in a recording medium, the following improvement is required.
Although a recording medium with aluminum hydrate has excellent ink absorptivity due to capillary phenomenon, the recording medium is significantly affected by environmental humidity. Therefore, this recording medium has a problem that the ink absorptivity is remarkably lowered under high-humidity environment because it absorbs environmental moisture.
In Japanese Patent Application Laid-Open No. 7-76161, use of boric acid is described. Nevertheless, this method causes a problem with long-term stability of coating liquid, and further requires a thermal curing process for sufficient reaction, and hence this leads to cost increase.
In addition, in Japanese Patent Application Laid-Open No. 7-276784, it is described to form firm bonding with a pigment (silica) by performing silanol-modification of a binder. However, according to the present inventors"" investigation, it has been shown that if the aluminum hydrate having the excellent characteristics described above is used as a pigment, the aluminum hydrate can not exhibit sufficient effects and has a problem with ink absorptivity after a storage especially under a high-temperature and high-humidity environment.
Furthermore, in Japanese Patent Application Laid-Open No. 9-76628, a combination of aluminum hydrate and a coupling agent is described.
On the other hand, it is described in Japanese Patent Application Laid-Open Nos. 6-227114 and 10-094754, European Patent Application Laid-Open No. 803375A1 or the like to use a resin binder in emulsion form. However, if the binder is used in emulsion form, the ink absorptivity certainly increases more than that of a water-soluble binder, but binding strength with the aluminum hydrate is remarkably lowered. Therefore, ordinary waterproof as well as the ink absorptivity after storage under a high-temperature and high-humidity environment degrades.
A object of the present invention is to provide an recording medium having excellent shelf life and ink absorptivity under a high-humidity environment, wherein its ink receiving layer has transparency, image density is thick, hue is clear, resolution of an image is good, and to provide image formation method using the recording medium.
In addition, another object of the present invention is to provide a production method of such a recording medium.
The present inventor et al. earnestly performed investigation so as to solve the above problems, and in consequence, completed the present invention.
Thus, the present invention provides a recording medium having an ink receiving layer on its base material, wherein the ink receiving layer is obtained by coating the base material withdispered liquid containing aluminum hydrate, a coupling agent, and resin emulsion having hydrolyzable groups expressed by the following general formula (1):
xe2x80x94MRn(ORxe2x80x2)3xe2x88x92nxe2x80x83xe2x80x83(1)
where R and Rxe2x80x2 represent hydrogen or alkyl groups, which may be either identical or different; n represents an integer from 0 to 2; and M represents Si, Ti, or Zr.
In addition, the present invention provides an image formation method for forming an image with ejecting ink from minute orifices to attach the ink on a recording medium, wherein the recording medium described above is used.
Moreover, the present invention provides a production method of a recording medium that is produced by forming an ink receiving layer on a base material, wherein the ink receiving layer is formed by coating on a base material dispersed liquid containing aluminum hydrate, a coupling agent, and resin emulsion having a hydrolyzable group expressed by the above-described general formula (1) and thereafter drying the recording medium.